[ J 72 ] 
the fame Direction, with an equal and uninterrupted 
Motion : For the Contrivance is fuch, that the Inftant 
one ceafes to act, the other begins, and fo on. 
A fine Chain goes twice round each Wheel, 
having at one End a Weight, x, ^always out of 
Water, which equiponderates with y at the other 
End, when kept floating at the Surface of the Water 
in the Veffel £, which/ muft always be. The two 
Cups zz, one at each End of the Balance mm, 
keep it in Equilibria, till one of them is forced down 
by the Weight and Impulfe of the Water, which it 
receives from the Tantalus s t i: Each of thefe 
Cups zz, has likewife a Tantalus of its own hh, 
which empties it after the Water has done running 
from g, and leaves the two Cups again inzyEqnilibrios 
q is a Drain to carry off the Water. 
Fig. 2. 
The Front of the Clepfydra 
Reprefents the Dial-Plate, with the Hour and Mi- 
nute-Hands, the Weight and Float belonging to n 2. 
The Front of the Tantalus in^ 2, marked sti, of 
which s the Mouth is 1 8 Inches above the Bottom of 
the Veffel g, and 18 Inches below the Top of the 
T ant alas t. i is the iffuing Leg of the Tantalus , 
which difcharges the Water out of the Veffel g into 
the Cup z, as foon as it runs over the Top t, till the 
Water finks as low as s. 
Fig> 3 . 
The Profile of the Clepfydra. 
T AB. 
